Single Letter Stock Symbols

If you have been following my blog for a while, you have noticed that I usually include stock market trivia relating to personalized stock symbols, similar to personalized license plates. But what about the single letter stocks symbols? Can you figure out why these companies chose these symbols? The following is a list of stocks with single letter symbols.

A AGILENT TECHNOLOGIES INC.
B BARNES GROUP INC.
C CITIGROUP INC.
D DOMINION RESOURCES
E E N I SPA ADR
F FORD MOTOR CORP.
H REALOGY CORP.
K KELLOGG CORP.
N former symbol for INCO LTD.
O REALTY INCOME CORP.
Q QWEST COMMUNICATIONS INTERNATIONAL INC.
R RYDER SYSTEM INC.
S SPRINT NEXTEL CORP.
T AT&T
X UNITED STATES STEEL
Y ALLEGHANY CORP.

As you can see, G, I, J, L M N, P U, V, W, and Z are currently unassigned.